The experimental work of Franklin, Price & Williams (1973) shows that for moderately large driving amplitudes there are features of spatial resonance that are not predicted by the model representation of Mahony & Smith (1972). We here derive an alternative model, which remains valid for moderately large driving amplitudes, and we are able to obtain a theoretical description of both hysteresis and nonlinear detuning of the low frequency wave response. An experiment in which surface waves were generated by a sinusoidal pressure field at the free surface (and which corresponds almost exactly to the theoretical problem) was conducted in order to test these predictions.

Measurements of the spectral components of turbulent momentum transfer for fully developed pipe flow are presented. The results indicate that near the wall (y+ < 15) two types of momentum transfer processes occur. A net positive transfer takes place in the higher frequency range of the energy-containing part of the turbulence spectrum whereas a net negative transfer returns low momentum to the wall region at the lower end of the spectrum. Examination of the turbulence at various y+ shows that the significant features of the turbulence spectra scale on frequency at any given Reynolds number, thus leading to an interpretation of the flow structure which is consistent with the hydrogen-bubble visualization data of Runstadler, Kline & Reynolds (1963). The results are consistent with a flow model in which disturbances extend from the sublayer to the core of the flow. Recent turbulent heat transfer measurements are also interpreted successfully by this model.

Experiments were carried out using models having L/D [les ] 2 and the resulting pressure distributions and vortex shedding characteristics are presented. A simple visualization technique which provides explanations of some of the measured results is described. It is concluded that splitter planes reduce the drag markedly by stabilizing the separation points and produce a wake narrower than that for a plain cylinder, raise the base pressure by as much as 50% and affect the Strouhal number to a lesser degree. Careful measurement techniques have enabled these effects to be presented accurately.

An inviscid Kármán-type vortex-shedding model is employed to show that multiple modes of vortex streets are possible, for flow around a given obstacle. This is in confirmation of various experimental observations in recent years, which were challenged by opposing claims that these were due to experimental inaccuracies.